Pulp screen



H. D. WELLS PULP SCREEN Dec. 1, I931.

Filed Dec.

Witness Harold 1). 77 6 Z$ agar/14m n a screen which Patented Dec. 1, 1931 HAROLD 1D. 01' GLENS FALLS, NEW YORK rum Application filed December 7, 1929. Serialli'o. 412,525.

This invention is designedto provide a pulp screen for handling a wide variety of pulp, such as paper stock, sulphite pulp, soda ulp, sulphate pulp groundwood pulp,

and efibered waste aper. It is further designed to produce er quality pulp than other screens, by combining inward flow screening and centrifugal separation. This action is further accomplished by a gentle screening action, while at the same time, the paper making fibre is removed from the stock and none of it left in the tailings which are rejected and dischar ed.

Objects of the invention are to provide asses only the best quality paper making bre and thoroughly cleans the stock; to provide a completely enclosed screening apparatus preventing the entrance offoreign matter into the-stock and overcoming any danger of spilling during the screenm operation; to provide an apparatus in w ich no air is mixed withthe stock in the screen, in which there is no foaming and in which no lumps are formed; to provide a screen requiring no concrete or other latform and one whlch may be installed irectly upon the main floor of a factory and may discharge at any desired point above the machine proper; screen in which the motion is entirely rotary, one in which no fresh water is needed, one embodying no shower pipes with consequent danger of clogging, one of continuous operation and em odying no revolving plates, and one of extremely simple, ractical construction which will be rugge and eflicient and well suited to the requirements of economical operation, convenient manipulation and ready accessibility for repair purposes. With the foregoing and minor objects in vlew, the invention resides in the novel sub ject matter hereinafter described and claimed, description being accomplished by reference to the accompanying drawings.

' Fig. 1 is substantially a central vertical longitudinal sectional view through a pulp screen constructed in accordance with my invention. a

Fig. 2 is a vertical transverse sectional view on line 24-2 of Fig. 1.

' Plate- 15 is provided to fprovide a;

.which may if desired A cylindrical casing 3 is provided, embodyingone end wall 4, a second end wall 5, and a continuous side wall formed of sections. Both end walls 4 and 5 are preferably in the form of castings, provided with suitable supporting feet 6. End wall 4 is provided with a volute pulp inlet 7 communicating by means of a slot 8 with the interior of the cylinder 3 and serving to swirl the pulp as it enters the cylinder, said inlet 7 being provided a; with a flange 9 instrumental in attaching a steam pipe or the like thereto. The end wall 5 is provided with a screened pulp outlet opening 10 whose peripheral edge is spaced inwardly from the casing side wall, said cl opening 10 being in communication with an external passage 11 which is flanged at 12 for connection with a conducting line for the screened pulp. In the present showing, the passage 11 is provided with a clean-out 13 7c and with a drain 14.

The side wall of the casing 3 embodies a lower longitudinal plate 15, an upper longitudinal plate 16, both of these plates being flanged and secured by cap screws or the like 17 to'the end walls 4 and 5, and two arcuate sheet metal side wall sections 18 secured to the plates 15 and 16, by bolts or the like 19. with an opening 20 be provided with a valve plate or the like 21 having any desired operating means not shown. This opening 20 may either constitute a tailings outlet-or a clean-out, as may be desired. The top plate 16 is provided with a tailings outlet 22 which is preferably provided with'alip 23 to intercept the swirling tailings and direct them through said outlet.

Within and concentric with the cylinder 3, is a cylindrical openwork screen frame 24 which embodies a closed end 25, an open end provided with a ring 26 of.T-shape in transverse section, and a side wall portion whichconsists of longitudinal bars 27 integral with rin s 28, the ends of said bars being integral W151 the closure 25 and the ring 26 respectively. A portion of this ring is snugly received in the opening 10 and its outstanding flange is secured by cap screws or the like 29to the end wall 5. Secured to the outer side of the 10.

frame 24 and forming therewith a cylindrical pulp screen, are a number of arcuate screen plates which may be secured to said frame by screws or in other desired ways.

The closed end 25 of the pulp screen frame, is inwardly spaced from the end wall 4 of the casin 3, and a scraper driving disk 31 is rotatably mounted in the space between said parts 25 and 4. Annular scraping means is secured to the disk 31 and surrounds the pulp screen. In the present showing this scraping means embodies a plurality of scraper bars or blades 32 extending longitudinally of the screen side wall and disposed at the exterior of the latter, said bars or blades being joined at one end to a ring 33, at their other ends to a ring 34, and between their ends to a plurality of rings 35. Ring 34 is .secured by cap screws or the like 36 to the disk 31. The other rings 33 and surround the screen and the ring 33 is disposed against the peripheral flange of the ring 26 above described. This ring 33 is preferably provided with a lining 37 of soft rubber which contacts with the screen plates 30 and serves as an effective, anti-vibratory bearingfor the end of the annular spacing means remote from the disk 31. This annular scraping means, if desired, may be circumferentially divided into sections. For illustrative purposes, each of the rings 33, 34 and 35 is shown divided into two sections, and releasable connections 38 and 39 are shown between said sections of the rings 33 and 35 respectively, no such connections being needed between the sections of the ring 34 in view of the fact that these sections are secured directl to the disk 31. It may be explained that the connections 38 and 39 are merely shown for illustrative purposes and that any other desired connecting means could be employed instead.

Removal of either side wall section 18 gives access to the annular screen scraping means so that the sections of the latter may be disconnected from each other and disconnected from the disk 31, allowing said sections to readily be removed, for instance, when repairs are necessary. 'When the entire scraping means is thus removed, the ring 26 may be disconnected from the end wall 5 and the entire screen and its frame 24 may be removed for repairs or for any other reason.

Any appropriate means may be provided for mounting and driving the disk 31. In the present showing, this disk is provided with an outwardly projecting hub 40 which is keyed at 41 upon a longitudinal shaft 42, said hub being within a stufling box 43 with which the end wall 4 is provided. Shaft 42 is disposed at one end of the machine only and is mounted in appropriate bearings 44 carried by a bracket 45 which may well be integral with the end wall 4. A pulley 46 is shown on shaft 42 for driving the same but other eaaaos provision may of course be made for this purpose.

In operation, while the screen scraping means 32, etc. is rapidly rotated, the pulp to be screened is introduced through the volute 7 which starts the pulp swirling in the direction in which said scraping means is being rotated. The liquid and all sufficiently fine particles of pulp pass through the screen plates 30 to the interior of the screen and are discharged from the machine through the outlet passage 11, while the tailings are dis charged at 20, 22, or at both locations. The scraping blades 32 terial. from adhering to the peripheryof the screen and clogging the latter, and these blades are so pitched that they tend to throw the pulp centrifugally, thus further aiding in keeping the screen clean. Moreover, When ever any blade 32 passes a given point, the liquid pulp which was previously thrown out by said blade, immediately returns toward the screen, so that an oscillatory or reciprocatory motion is constantly given to the liquid in a direction radially of the screen, thereby further aiding in the screening action and assisting in preventing screen clogging.

It will be seen from the foregoing that a rather simple and inexpensive construction has been provided for carrying out the objects of the invention, and while the structure herein disclosed is preferably followed, it is to be understood that within the scope of the invention as claimed, variations maybe made.

I claim 1. A pulp screen comprising a stationary cylindrical casing having a pulp inlet and a tailings outlet, one end wall of said casing being provided with a screened pulp outlet inwardly spaced from the casing side wall, a cylindrical screen having a closed end and an open end, said screen having its side wall inwardly spaced from said casing side wall and having its open end secured to said one end wall of the casing around said screened pulp outlet, the closed end of said screen being inwardly spaced from the other end wall of said casing, a scraper-drivinghea'd rotatably mounted in the space between said closed end of said screen and said other end wall of the casing, means for driving said head, and screen scraping means secured to said head and disposed at the exterior of said screen side wall.

2. A pulp screen comprising a stationary cylindrical casing having a pulpinlet and a tailings outlet, one end wall of saidcasing inwardly spaced from the casing side wall, a cylindrical screen having a closedend and an open end, said screen having its side wall inwardly spaced from said casing side wall and having its open end secured to said one end wall of'the casing around said screened pulp outlet, the closed end of said screen beprevent the coarse ma- .being provided with a screened pulp outlet said cylindrical ing inwardly spaced from the other end wall of said casing, a scraper-driving head rotatably mounted in the space between said closed end of said screen and said other end wall of the casing, means for driving said head, screen-scraping blades secured to said head and disposed longitudinally at the exterior of said screen side wall, and annular spacing means connected with said blades and surroundingsaid screen side wall.

3. A pulp screen comprising a stationary casing having a pulp inlet and a tailingsoutlet, one end wall of said casing being provided with a screened pulp outlet inwardly spaced from the casing side wall, a cylindrical screen having a closed end and an open end, said screen having its side wall. inwardly spaced from said casing side wall and having its open end secured to said one end wall of the casing around said screened pulp outlet, the closed end of said screen being inwardly spaced from the other end wall of said casing, a scraper-driving head rotatably mounted in the space-between said closed end of said screen and said other end wall of the casing, means for driving said head,

screen-scraplng blades secured to said headand disposed longitudinally at the exterior of screen side wall, a ring connecting the ends of said blades adjacent said one end wall of the casing, and an elastic lining for said ring contacting with said screen side wall.

4. A pulp screen comprising a stat onary cylindrical casing having a pulp inlet and a tailings outlet, one end wall of said casing being formed with a screened pulp outlet opening whose peripheral edge is inwardly spaced from thecasing side wall, an openwork. cylindrical screen frame having an open end and a closed end, said frame being inwardly spaced from the casing side wall and having a ring at its open said one end wall of the casing around said screened pulp outlet, the closed end of said said closed end of said frame and said other end wall of the casing, means for driving said head, and screen-scraping means secured to said head and surrounding said screen. 7

5. A pulp screen comprising a stationary cylindrical casing having a pulp inlet and a tailings outlet, one end wall of said casing being provided with a screened pulp outlet inwardly spaced from the casing side wall, a cylindrical screen having a closed end and anopen end, said screen having its side wall inwardly spaced from said casing side wall and having its open end wall of the casing around said screened pulp outlet, the closed end of said screen being inwardly spaced from the other end end secured to end secured to said oneing frame surrounding said screen and composed of arcuate sections secured to each other and secured to said disk.

6. A pulp screen comprising a stationary t cylindrical casing having a pulp inlet and a tailings outlet, one end wall of said casing being formed with a screened pulp outlet opening whose peripheral edge is inwardly spaced from the casing side wall, an openwork cylindrical screen frame having an open end and a closed end, said frame being inwardly spaced from the casing sidewall and having a ring at its open end secured to said one end wall of the casingaround said screened pulp outlet, the closed end of said frame being inwardly spaced from the other end wall of said casing, arcuate screen plates secured to said frame and forming therewitha cylindrical pulpscreen, ascraper driving disk rotatably mounted in the space between the closed end of said screen and said other end wall of the casing, means for driving said disk, and an annularropenwork screen-scrapposed of arcuate sections secured to each other and secured to said disk.

7 In a machine of the type described, the 1 combination of a fixed continuous screen through which the pulp flows inwardly, and centrifugal means rotatable around the screen for effecting pulp separation around said screen. 4 e

8. In a machine of'the type described, the combination of a fixed continuous screen through which the pulp flows inwardly, and means independent of the screen for pulsating the pulp radially of said screen.

9. A pulp screen comprising a fixed continuous-walled screen, a pulp container around said screen,- driven pulp-agitating means at the outer periphery of said screen, and a screened pulp on let from the interior of said screen. I

10. A pulp screen comprising a fixed continuous-walled screen, a pulp the interior of said screen.

In testimony whereof I have i hereunto aflixed my signature. 1

1 HAROLD. D. WELLS.

container 7 around said screen, rotary pulp agitating 

